In the manufacturing of magnetic coupling coils for new energy vehicles (such as wireless charging magnetic coupling systems, high-performance drive motors, or high-frequency transformers), closed-loop fine-tuning CNC close-winding is a core high-precision process. Given the stringent requirements of new energy vehicles for high power density, high conversion efficiency (Q-factor), and long-term vibration resistance, special attention must be paid to the following key aspects during the implementation of this process:

Magnetically Coupled Coils OEM for New Energy Vehicles | WIRESUN

I. Parameter Settings for the Closed-Loop Control System

The closed-loop fine-tuning system relies on a dynamic cycle of “real-time sensor detection – controller algorithm calculation – actuator fine-tuning.” The core considerations here are “accuracy” and “speed”:

• Dynamic Compensation for Tension Closed-Loop Control:

During the winding of magnetically coupled coils (especially non-circular, track-shaped, or rectangular coils), the rotational radius at various points on the coil changes in real time, causing high-frequency fluctuations in wire tension.

• Key Point: A low-inertia, high-response electronic tensioner must be used in conjunction with PID algorithms for feedforward compensation. Tension fluctuations should be controlled within ±1% of the rated tension to prevent enameled wire from being stretched thin due to excessive tension (resulting in increased resistance and altered magnetic properties) or becoming loose due to insufficient tension.

• Micrometer-level fine-tuning of wire positioning (CCD vision closed-loop):

Use a high-resolution industrial camera to capture the contact gap between the current turn of wire and the previous turn in real time.

• Key Considerations: The lighting source for the vision system must avoid misjudgments caused by the high reflectivity of enameled wire. The algorithm must filter out noise caused by minor surface imperfections in the wire in real time, and the response steps of the fine-tuning shaft (typically a linear motor-driven wire-laying shaft) must reach the micrometer level to ensure that the tracking compensation does not lag.

II. Synergy of the Physical Properties of Wire and Frame

Precision CNC close-winding depends not only on the machine but also heavily on the physical feedback from the materials:

• Deformation control of multi-strand Litz wire:

To reduce the skin effect and proximity effect, magnetic coupling coils for new energy vehicles commonly use multi-strand Litz wire consisting of hundreds or even thousands of strands.

• Key Considerations: Since Litz wire has a near-circular cross-section and a relatively soft texture, it is highly prone to “flattening” or “disordered deformation” during winding and compression. The wire spacing in the CNC program cannot simply be equated with the wire’s nominal outer diameter; a “wire compression factor” must be incorporated, and the actual width occupied per turn must be corrected via a closed-loop system during the first trial winding.

• Stator Frame Rigidity and Deformation:

The cumulative radial compression force from hundreds of tightly wound turns is immense, sufficient to cause inward centripetal shrinkage of the plastic stator frame.

• Key Considerations: Even slight deformation of the bobbin will cause misalignment in the winding pitch of subsequent layers. Before winding, the rigidity of the bobbin material (e.g., PBT + glass fiber, liquid crystal polymer LCP) must be evaluated. If necessary, incorporate layer-by-layer pitch reduction compensation into the CNC program, or install an expandable internal support on the winding shaft.

III. “Damage Prevention” and Arrangement Control During the Process

The ultimate goal of high-density winding is to achieve optimal duty cycle and insulation reliability:

• Strictly prevent wire kinking and varnish damage: The bending radius at corners is typically small for magnetically coupled coils.

• Key Points: Strictly limit the minimum radius of wire-guiding rollers and wire-laying nozzles (typically required to be 3–5 times the wire diameter). All roller surfaces must undergo ultra-mirror polishing or Teflon coating to prevent high-speed friction between the rollers and the wire from scratching the varnish during frequent closed-loop fine-tuning, which could lead to inter-turn short circuits in the final product.

• Fine-tuning for layer-crossing jumps and tail-ending:

The transition from the first layer to the second (i.e., the layer-change lift point) is the area where wire routing is most prone to confusion.

• Key Point: During layer changes, the CNC wire-laying spindle must execute a **“sudden jump at a specific angle”** rather than a smooth transition. This forces the wire to complete the layer change within an extremely short angular range, ensuring that the second layer’s wiring can quickly enter the “V-groove” of the previous layer, thereby preventing wire overlap or crossing.